Plus, if you live in GWS you get $5k/year and I think you can go for extra scholarships too.
That being said, my reply did not take into account the fact that graduating from the PhD stream at USyd actually will help you gain a place in the more competitive speciaties. Let's not be politically correct, do you really think doctors in medical research do 0 clinical work and settle for a salary below that of a McDonald's Manager? The vast majority of research is conducted by specialists who are obligated to do it, meaning a PhD will significantly reduce the time required to become a consultant.